The present invention relates to a method of treating a semiconductor substrate.
In a manufacturing process of a semiconductor device, there are included various processes such as a lithography process, an etching process, an ion implanting process and the like. Before moving into the next process after finishing each of the processes, there is executed a cleaning (washing) process and a drying process for removing an impurity and residue remaining on a wafer surface so as to make the wafer surface clean.
In recent years, in accordance that a critical dimension is miniaturized, there has been generated a problem that a resist pattern collapses due to a capillary phenomenon upon developing and drying the resist pattern after the lithography process (exposure and development). In order to solve the problem mentioned above, there has been proposed a method of making the surface of the resist pattern hydrophobic surface so as to lower capillary force acting between the resist pattern, and developing solution and rinsing pure water (refer, for example, to Japanese Patent Application Laid-open No. 7-142349). In this method, an organic material adheres on the surface of the resist pattern, however, the organic material is removed together with the resist pattern in an dry etching process after the lithography process.
Further, in a cleaning treatment of a semiconductor wafer after the dry etching process, a chemical solution for the cleaning treatment is supplied to the surface of the wafer, and thereafter a rinse treatment is performed by supplying pure water to the surface of the wafer. After the rinse treatment, there is performed a drying treatment for removing the pure water left on the wafer surface and for drying the wafer. As a method for performing the drying treatment, there is, for example, a method of drying the wafer in such a manner that IPA (isopropyl alcohol) is used to substitute the pure water on the wafer with IPA (refer, for example, to Japanese Patent No. 3866130). However, there is a problem that a pattern formed on the wafer is collapsed by the surface tension of the solution during the drying treatment.
Further, even if Hydrofluoroether (HFE) having lower surface tension than the IPA is used, it has been difficult to suppress the pattern collapse. In order to solve the problem mentioned above, there has been proposed supercritical CO2 drying by which the surface tension comes to zero. However, the supercritical CO2 drying is difficult to be applied to mass production process, and in the case that water content or the like is brought into a chamber achieving a supercritical atmosphere, there has been a problem that it is impossible to prevent the pattern from collapsing.